Meeting Abstract
Gopher tortoises display large chin glands that have been suggested to be a courtship cue, through visual gland size or production of olfactory signals. Little is known about the function of this gland except that males have larger glands than females. While males are thought to use head bobbing to transmit odors via these glands to attract females or ward off other males, females only head bob in courtship, suggesting a potential sexual dimorphism in sensory awareness of chin gland cues. In this study, courtship and male competition were simultaneously observed in presentation (non-visual and visual) of a female with two males of differing sized chin glands (N=5-7). Types and duration of behaviors were recorded during 10 minute trials during the tortoise breeding season (April-September) and classified into 3 categories: regulatory (eating), stress (pacing), or awareness (sniffing, awareness of other conspecifics). A significant behavior category*month interaction was found in which both sexes (sexes did not differ by month in behavior category, p=0.74) exhibited more stress behaviors in April than in June and more awareness behaviors in June than in April (p=0.003). In August, both sexes exhibited more awareness behaviors, while in September, they displayed more regulatory behaviors (p=0.03). Because chin glands also show a seasonal pattern of growth, with enlargement in June and regression in September, this glandular regression coincided with a shift toward regulatory behavior, suggesting hormonal control. There was also a sex*treatment interaction seen between April, June, and July due to female tortoises exhibiting stress behaviors in the non-visual presentation in June (p=0.05). Furthermore, both males and females spent more time sniffing during the non-visual presentations than in the visual presentations (p=0.02). While males did sniff more than females over all months, dimorphism in active sniffing was not found (p=0.55).
